1. Field of the Invention (Technical Field)
The present invention relates to methods and apparatuses for controlling and permitting communications between components of robotic systems.
2. Background Art
Technical advances in the field of robotics have occurred at an enormous rate during the past three decades. Unfortunately, the advances have occurred in a technological environment requiring generation of hardware and software substantially from scratch for each actual robotic system. This is due to the fact that no general modular architecture exists for development of robotic systems.
It has not heretofore been possible to design components of robotic/telerobotic control systems independently. Instead, the entire system had to be analyzed as a whole. Furthermore, because of the inherent nonlinearities of telerobotic systems, the difficulties involved in sampling, and the complexity of such systems, there was a practical limit to the number of features that could be included in such systems.
The present invention relates to several topics in the robotics literature, including open architecture control systems, telerobotic control systems, passivity based control systems, sensor integration, graphical control, and impedance control.
A number of researchers have introduced open architecture control systems for robots based on UNIX and C. Some have involved use of generic robot controllers. V. Hayward and R. Paul, "Robot Manipulator Control Under UNIX RCCL: A Robot Control `C` Library," International Journal of Robotics Research, vol. 5, pp. 94-111, 1986; L. Salkind, "The SAGE Operating System," IEEE International Conference on Robotics and Automation, pp. 860-865, 1989; E. M. Sollbach and A. A. Goldenberg, "Real-Time Control of Robots: Strategies for Hardware and Software Development," Robotics & Computer-Integrated Manufacturing, vol. 6, pp. 323-329, 1989; D. B. Stewart, D. E. Schmitz and P. K. Khosla, "Implementing Real-Time Robotic Systems Using CHIMERA II," IEEE International Conference on Robotics and Automation, pp. 598-603, 1990. Others have developed high-level interfaces to existing controllers. D. J. Miller and R. C. Lennox, "An Object-Oriented Environment for Robot System Architectures," IEEE International Conference on Robotics and Automation, pp. 352-361, 1990. These systems have been designed primarily for robotic control, and thus focus on issues such as task planning, programmability, and sensor interfacing. The present invention does not plan tasks nor optimize the control architecture for particular sensors. Instead, it provides an intuitive, reconfigurable environment for telerobotics, with ample capability for incorporation of a high-level task planner.
In the area of telerobotic control architectures, a number of open architectures have been proposed for controlling unilateral systems, i.e., those in which the operator is not dynamically coupled to the robot. P. T. Boissiere and R. W. Harrigan, "An Alternative Approach to Telerobotics: Using a World Model and Sensory Feedback," Third Topical Meeting on Robotics and Remote Systems, pp. 1-9, 1989; R. A. Brooks, "A Robust Layered Control System for a Mobile Robot," IEEE Journal of Robotics and Automation, vol. RA-2, pp. 14-23, 1986; S. Graves, L. Ciscon and J. D. Wise, "A Modular Software System for Distributed Telerobotics," IEEE International Conference on Robotics and Automation, pp. 2783-2785, 1992; R. Lumia, J. Fiala and A. Wavering, "The NASREM Robot Control System Standard," Robotics & Computer-Integrated Manufacturing, vol. 6, pp. 303-308, 1989. The present invention works at a lower level than unilateral control systems and provides a framework for developing sophisticated real-time dynamic behavior in bilateral telerobotic systems.
Work has been done in building high-performance bilateral teleoperation systems using special purpose hardware. P. G. Backes and K. S. Tso, "UMI: An Interactive Supervisory and Shared Control System for Telerobotics," IEEE International Conference on Robotics and Automation, pp. 1096-1101, 1990; A. Bejczy and Z. Szakaly, "Universal Computer Control System (UCCS) for Space Telerobots," IEEE International Conference on Robotics and Automation, pp. 318-324, 1987; S. Hayati, T. Lee, K. Tso and P. Backes, "A Testbed for a Unified Teleoperated-Autonomous Dual-Arm Robotic System," IEEE International Conference on Robotics and Automation, pp. 1090-1095, 1990. The present invention works at a higher level than these bilateral systems, allowing greater discretion in choosing robots and sensors, and also looser couplings between master and slave.
The underlying control equations of the present invention are based on passive two-port elements. Passive system behaviors have long been used as a model for controlling autonomous systems, N. Hogan, "Impedance Control: An Approach to Manipulation," ASME Journal of Dynamic Systems and Control, vol. 107, pp. 1-7, 1985, and have recently been applied to bilateral continuous teleoperation systems. R. J. Anderson and M. W. Spong, "Bilateral Control of Teleoperators with Time Delay," IEEE Transactions on Automatic Control, vol. 34, pp. 494-501, 1989; J. E. Colgate, "Power and Impedance Scaling in Bilateral Manipulation," IEEE International Conference on Robotics and Teleoperation, pp. 2292-2297, 1991; G. Raju, G. C. Verghese and T. B. Sheridan, "Design Issues in 2-port Network Models of Bilateral Remote Manipulation," IEEE International Conference on Robotics and Automation, pp. 1316-1321, 1989. A passive telerobotic controller can be proved stable in spite of the non-linear behavior of the operator, the robot, and the environment. R. J. Anderson and M. W. Spong, "Asymptotic Stability for Force Reflecting Teleoperators with Time Delay," The International Journal of Robotics Research, vol. 11, pp. 135-149, 1992.
The present invention is of a discrete real-time architecture providing for both stability and modularity of robotic systems. The invention solves the problems discussed above.